The present invention relates in general to winning machines for winning minerals, coal or the like.
More particularly, this invention pertains to a rotating cutting roller for such a winning machine.
Even more particularly, the present invention relates to a spraying nozzle system operated for suppressing coal dust produced during the winning operation.
It is known that, when a cutting drum provided with a plurality of cutting picks or bits is utilized in the winning machine, spraying nozzles are used for individual picks which spray water onto the picks of the rotating drum to suppress mineral or coal dust produced during the underground mining. Spraying jets applied by the nozzles to the cutting picks are usually so directed that about one third of the free length of the individual pick is stricken by the spraying jet. Thereby the pick is substantially cooled and its service life is increased. The spraying water is normally supplied to the periphery of the cutting drum or roller from the water supply source through the tubular support of the cutting roller. Water is then fed from the tubular support, namely from a special conduit provided in the interior of the tubular support, to fluid distribution channels or passages which are arranged in the foot areas of the helical blade and the locking ring of the cutting roller, adjacently to the outer circumferential surface of the tubular support. Such a fluid distribution passage is usually formed either in the foot area of the locking ring and extends in the circumferential direction of the locking ring or is immediately cut in the foot area of the respective blade and extends according to the shape of the blade in the direction of the outer surface of the tubular support. Individual holes are made in the cutting roller, which extend from the distribution passages to the spraying nozzles. Radial connecting channels or passages formed as deep bores can be also provided in the cutting roller between the fluid distribution passages and the nozzles.
German Offenlegungsschrift No. 2,261,206 discloses a cutting drum for a winning machine, which is provided with a number of helical blades formed of segments. The cutting drum has a fluid distribution channel which extends circumferentially of the respective blade and is radially spaced from the outer surface of the body of the drum. The fluid distribution channels for individual adjacent segments are not connected to each other.
German Offenlegungsschrift No. 2,032,846 describes a cutting roller, in which the fluid distribution channel is formed in the region of the blade, sheltered from the winds, inside of the free edge area of the blade extended transversally to the welded profile iron portion thereof, said channel extending in the circumferential direction of the blade. This fluid distribution channel formed as a conduit is held in position by clamping straps. The disadvantage of this otherwise satisfactory construction is that it has unfavorable loading effect on the blade due to the welded profile iron portion and because of the unfavorable arrangement of the elongated fluid distribution conduit in the area of the outer periphery of the blade, and wherein the clamping straps present a further source of disturbance. The construction expenses in this design are extremely high and thus manufacturing costs are high, respectively. A further disadvantage of the cutting drum described in this German publication is a possibility of blocking of the channel system due to possible corrosive sediments. Furthermore, a multiple coiled fluid supply conduit formed as a hose is provided in this known construction, which should be disposed in the interior of the body of the cutting drum. A similar construction is disclosed in German Pat. No. 1,242,539, this structure being also very expensive.
German Pat. No. 1,272,257 shows a cutting drum or roller in which pick holders extend in the circumferential direction of the blade and are welded to the blade by the fluid distribution conduit formed as a U-iron piece, or are connected to the blade by a weld seam by means of a tubular profile iron piece which in turn is connected, also by welding, to the fluid distribution conduit. This construction is disavantageous in that cracks may be formed in the structure which would lead to leakage in the fluid distribution conduit. Spraying nozzles in this construction direct the spraying jets also unfavorably, namely onto the free spaces rather than onto the picks so that the picks are not properly cooled whereby the service life of these picks is shortened and the picks must be replaced when worn out. The structure is also bulky due to the arrangement of its components on the free periphery of the blade.
British patent specification No. 1,309,005 discloses a rotary cutter for a mineral mining machine, in which water spraying conduits are formed of nylon tubes. The water spraying system of the British disclosure is very complicated and also very expensive in manufacturing.
German patent publication No. 27 25 8726 discloses a cutting roller for a winning machine, in which water spraying system includes a water distribution passage extended circumferentially of the helical blade of the roller, and a radially extended bridging passage to which water or cooling fluid is supplied from a fluid supply passage arranged in the interior of the tubular support of the roller. The fluid spraying system is also provided with connection channels which extend from the fluid distribution passage to individual spraying nozzles. Since the fluid distribution passage is spaced radially outwardly from the outer face of the tubular support forces generated at the weld seam at the foot of the blade act so that they do not unfavorably affect that seam. Furthermore, the manufacturing of such a fluid spraying system presents no problems because the fluid distribution passage is made by milling a groove in the body of the blade. To close such a groove a sheet-like strip formed according to the shape of the groove is provided, which is connected to the body of the blade or the locking ring, if the groove is formed in the latter, by welding. All fluid conducting conduits formed in the cutting roller and including the fluid supply conduit, the fluid distribution conduit and the connection conduits which lead to individual spraying nozzles, have a corrosion-resistant lining or coating to prevent the formation of corrosive sediments on the interior surfaces of the entire fluid channel system. Due to the above arrangement the reliable operation of the whole fluid channel system is warranted. This also results in increase of cutting capacity of the cutting picks and in a longer service life of the picks, particularly in those cases when the whole cutting roller is made out of stainless steel, for example of NIROSTA or a suitable material containing chromium-molybdenium-manganese-nickle-steel.
Apparenty tubes or hoses of synthetic plastic material can be used in the fluid channel system for conducting a spraying fluid; such tubes or hoses should be tightly sealed at the transition or connection zones with each other by clamping straps. The cutting rollers in which such tubes can be utilized have the advantage that the whole channel system is protected against corrosion. However, even this structure has the disadvantage which resides in that it requires repair and cleaning of the interior of the channel system due to corrosion of covering strips and shields which are welded to the body of the blade or the locking ring. These repair and cleaning operations are bothersome and costly and should be usually carried out at work side.